For the present Gaia sample, we face the additional challenge that the classification
was
based on one frequency only, which makes the presence of contaminants in our sample
likely. In particular, rotationally modulated stars are prevalent at spectral
types A and B
[1]}, [2]}, [3]}, [4]}.
Bp and Ap stars tend to be
slow to moderate rotators showing
surface spots, leading to variability in the same frequency domain as g-mode pulsations.
On top of that, although the window function of Gaia time series is significantly better
than those of typical ground-based surveys, the highest peak in the normalised
spectral window
of the Gaia DR3 time series
can still reach 60% or more for certain regions in the sky.

We cannot therefore exclude
that a fraction of the low-frequency oscillators are actually \(\delta \)  Sct or
\(\beta \)  Cep stars for which an alias frequency was found instead of the true frequency.
Likewise, high-frequency oscillators might have been
classified as SPB or \(\gamma \)  Dor star
because of frequency aliasing (cf. Appendix A).
